Granules are widely used in food, pharmaceutical, agricultural, paint and chemical industries. Practically every tablet we take is granulated before it is made into a tablet. Household cleaning substances, fertilizers, animal feed, sugar, salt and just about every dry item that contains multiple ingredients is used in granule form.
There are dozens of reasons why granules are used and needed. The following are four of the main ones:
1. In multi-ingredient tablet manufacturing it is important that each tablet contains the same ratio of ingredients as the overall batch, otherwise the effectiveness of every tablet will be different. The only way to avoid this problem is to convert complex powder and liquid formulas into uniform granules that contain the correct ratio of ingredients, then press the tablets from these granules. There are two criteria in manufacturing a high quality tablet. One is compressibility, which is the ability to compress the granule to bind and form a tablet. The second criterion is content uniformity which is the ability to have the same ratio of ingredients distributed throughout the entire tablet.
2. Granules flow very easily due to their uniform size and moisture level. Fine powders clog, pack or clump, and do not flow well. Process machines do not work well with powders. A solution to this problem is to convert complex powder and liquid formulas to granules.
3. Fine powders do not mix into liquids easily. Experience shows that fine particles are more difficult to mix, they clump up and float in or on top of the liquid. One solution to this problem is to convert powders into granules.
4. When multiple component mixtures are transported, due to density differences in each ingredient, heavier ones will migrate toward the bottom and lighter ones will come to the surface. To prevent this from happening, mixtures are first converted to granules.
Granules can be formed in two ways; they can be ground from a larger solid mass and then sifted to obtain the proper granule size (size reduction). This process is called Granulation. The second method is to mix the various powdered ingredients with a liquid and a binder to form larger particles (size increase). This process is called Agglomeration.